For wireless power transmission, there has been known a method of connecting two coils so as to make their generating electromagnetic fields opposite. According to the method, the electromagnetic field generated around the coils can be reduced.
However, when using a plurality of coils, many factors such as inductance of each coil, characteristics of a part connected to each coil, characteristics of a counter device to which each coil transmits power, positional relation between the counter device all need to be symmetrical in the coils, otherwise, the amplitude of the current flowing in each coil does not become the same. Further, phases of the current flowing through the coils become different and the generated electromagnetic field does not become an opposite phase. As a result, effect of reduction in a leaked electromagnetic field is limited.